Heretofore, it has been considered that hyperlipemia caused by metabolic error of lipids results in arteriosclerosis and is one of the major dangerous factors causing ischemic heart disease or cerebral embolism
Recently, it was revealed that an enzyme, acyl-CoA: cholesterol acyltransferase (ACAT) acts an important role at lipid metabolism, especially cholesterol metabolism. It was also reported that compounds having an inhibitory activity of the enzyme, ACAT, actually inhibit the absorption of cholesterol at intestine, reduce the level of cholesterol in blood, and inhibit the deposition of cholesterol on arterial wall, and accordingly, are useful as therapeutical medicines for atherosclerosis as well as hyperlipemia, as described in Japanese Patent Application Laying-Open (Kokai) No. 16761/88, No. 93569/89, No. 6455/90, No. 6456/90, and No. 457/90.